The
decline in the world’s oil supply offers no sudden dramatic event
that would appeal to the writer of "apocalyptic" science fiction:
no mushroom clouds, no flying saucers, no giant meteorites. The future
will be just like today, only tougher. Oil depletion is basically just
a matter of overpopulation — too many people and not enough resources.
The most serious consequence will be a lack of food. The problem of
oil therefore leads, in an apparently mundane fashion, to the problem
of farming.

To what extent could food
be produced in a world without fossil fuels? In the year 2000, humanity
consumed about 30 billion barrels of oil, but the supply is starting
to run out; without oil and natural gas, there will be no fuel, no asphalt,
no plastics, no chemical fertilizer. Most people in modern industrial
civilization live on food that was bought from a local supermarket,
but such food will not always be available. Agriculture in the future
will be largely a "family affair": without motorized vehicles,
food will have to be produced not far from where it was consumed. But
what crops should be grown? How much land would be needed? Where could
people be supported by such methods of agriculture?

WHAT TO GROW

The most practical diet would
be largely vegetarian, for several reasons. In the first place, vegetable
production requires far less land than animal production. Even the pasture
land for a cow is about one hectare, and more land is needed to produce
hay, grain, and other foods for that animal. One could supply the same
amount of useable protein from vegetable sources on a fraction of a
hectare, as Frances Moore Lappé pointed out in 1971 in Diet for
a Small Planet [12]. Secondly, vegetable production is less complicated.
The raising of animals is not easy, and one of the principles to work
with is, "The more parts there are to a machine, the more things
there are that can go wrong." The third problem is that of cost:
animals get sick, animals need to be fed, animals need to be enclosed,
and the bills add up quickly. Finally, vegetable food requires less
labor than animal food to produce; less labor, in turn, means more time
to spend on other things. A largely vegetarian diet is also the most
healthful, but that is a separate issue.

With a largely vegetarian
diet, one must beware of deficiencies in vitamins A and B12, iron, calcium,
and fat, all of which can be found in animal food. Most of these deficiencies
are covered by an occasional taste of meat; daily portions of beef and
pork are really not necessary. Animal food should be used whenever it
is available, but it is not a daily necessity.

Of vegetable foods, it is
grains in particular that are essential to human diet. Thousands of
years ago, our ancestors took various species of grass and converted
them into the plants on which human life now depends. Wheat, rice, maize,
barley, rye, oats, sorghum, millet — these are the grasses people
eat every day, and it is these or other grasses that are fed (too often)
to the pigs and cows that are killed as other food. A diet of green
vegetables would be slow starvation; it is bread and rice that supply
the thousands of kilocalories that keep us alive from day to day.

In general, the types of
crops to grow would be those which are trouble-free, provide a large
amount of carbohydrates per unit of land, provide protein, and supply
adequate amounts of vitamins and minerals. Most grains meet several
of these requirements. Winter (not summer) squashes are also high in
kilocalories. Parsnips rate high in kilocalories, whereas carrots, turnips,
rutabagas, and beets are slightly lower on the scale. Beans (as "dry
beans") rate fairly well in terms of kilocalories, and they are
the best vegetable source of protein, especially if they are eaten with
maize or other grains with complementary amino acids.

HOW MUCH LAND?

The amount of land needed
for farming with manual labor would depend on several factors: the type
of soil, the climate, the kinds of crops to be grown. The highest-yielding
varieties are not necessarily the most disease-resistant, or the most
suitable for the climate or the soil, or the easiest to store. The weather
also makes a big difference: too little rain can damage a crop, and
too much rain can do the same. Unusually cold weather can damage some
crops, and unusually hot weather can damage others. Without irrigation
— relying solely on rain — the yield is less than if the
crops were watered.

But here are some rough figures.
Let us use the production of maize (corn) as the basis for our calculations,
and for now let us pretend that someone is going to live entirely on
maize. "Maize" or "corn" here does not mean the
vegetable that is normally eaten as "corn on the cob," but
the types that are mainly used to produce cornmeal; these are sometimes
referred to as "grain corn" or "field corn." Maize
is very high-yielding and can be grown easily with hand tools, but it
is only practical in areas with long periods of warmth and sunshine;
even in most parts of North America it is not easy to grow north of
about latitude 45.

A hard-working adult burns
about 5,000 kcal per day, or 1.8 million kcal per year. David Pimentel
[14] mentions a study of slash-and-burn maize culture in Mexico that
produced 1,944 kg of maize per hectare, or 6.9 million kcal. Under such
conditions, then, a hectare of maize would support approximately 4 people.

Potatoes require about 50%
less land than "grain-corn" maize, but they are troublesome
in terms of insects and diseases. Wheat, on the other hand, requires
approximately 50% more land than maize to produce the same amount of
kilocalories. Beans require about 100% more land than maize. "Root
crops" such as turnips, carrots, or beets have yields at least
10 times greater than maize, but they also have a much higher water
content; their actual yield in kilocalories per hectare is slightly
less than that of maize.

To determine whether a country
can feed itself with manual labor, we need to look at the ratio of population
to arable land. With manual labor, as noted, a hectare of maize-producing
land can support only 4 people. Any country with a larger ratio than
that would be undergoing famine. The problem might be relieved to some
extent by international aid, but without fossil fuels for transportation
such international aid would be negligible. And this ratio is for maize,
a high-yield crop; we are also assuming that crops will not be wasted
by feeding them to livestock in large amounts.

In the present year of 2007,
the world as a whole has a population-to-arable ratio of slightly over
3:1. Conversely, less than a third of the world’s 200-odd countries
actually pass that test, and many of those are countries that have relatively
low population density only because they have been ravaged by war or
other forms of political turmoil. The Arabian Peninsula, most of eastern
Asia, and most of the Pacific islands are far too crowded. Even the
UK scores badly at 11:1. If we meld UN figures [17] with those of Gordon
and Suzuki [9] and assume that the world population in 2030 will be
about 11 billion, then even fewer countries will be within that 4:1
ratio. There might be serious conflicts between the haves and the have-nots,
and isolationism might be a common response.

SOIL FERTILITY

Most of the world’s
land is not suitable for agriculture. Either the soil is not fertile
or the climate is too severe. In most areas, if the soil is really poor
to begin with there is not much that can be done about it, at least
with the resources available in a survival situation.

Soil science is a complicated
subject. Roughly speaking, however, good soil contains both rock material
and plant material (humus). The rock material includes 16 elements of
importance: boron, calcium, carbon, chlorine, copper, hydrogen, iron,
magnesium, manganese, molybdenum, nitrogen, oxygen, phosphorus, potassium,
sulfur, and zinc. (Actually the C, H, and O are mainly from air or water.)
The plant material (humus) acts in 3 ways: (1) mechanically —
it holds air and water; (2) chemically — it contains a large amount
of C, H, and O, and a little (frequently too little) of the other 13
elements; and (3) biologically — it contains useful organisms.

Of the 16 elements, the most
critical are phosphorus (P), potassium (K), and especially nitrogen
(N); calcium and magnesium are probably next in importance. These elements
might be abundant in the virgin soil before any cultivation is done,
but wherever crops are harvested a certain amount of the 3 critical
elements is being removed. The usual solution is to add fertilizer,
which can be artificial or can come from such sources as rock dust.

As Donald P. Hopkins [10]
explained in 1948, (a) organic matter is not an ideal substitute for
(b) fertilizer (i.e. the 16 elements), nor is (b) fertilizer an ideal
substitute for (a) organic matter. A few centuries ago, animal manure
was high in N-P-K etc., but that is rarely the case today unless the
manure itself originates in feed that was artificially fertilized. Nevertheless,
in a survival situation, organic matter may be the only available source
of the essential elements.

Native people in many countries
had a simple solution to the problem of maintaining fertility: abandonment.
No fertilizer was used, except for the ashes from burned undergrowth
and from burned crop residues. As a result, of course, the soil became
exhausted after a few years, so the fields were abandoned and new ones
were dug. Sometimes such a technique is called "slash-and-burn."
On a large scale the technique would mean leaving behind a long string
of what used to be called "worked-out farms." For a large
population, such a method would be impractical, in fact catastrophic.
On a very small scale, however, it might be all that is possible; in
any case, the abandoned spot would, over many years, revert to reasonably
fertile land, at least in terms of humus content, and there might be
wild legumes to replace the nitrogen.

Actually, if abandoned land
is taken up again at a later date, the practice of abandonment tends
to overlap with that of fallowing, another practice to be found in many
societies. With the traditional European method of fallowing, part the
land is left to revert to grass and weeds for perhaps a year before
being plowed again.

A common partial solution
to the N-P-K problem has been to turn crop waste into compost and put
it back onto the land. The problem with that technique, however, is
that one cannot create a perpetual-motion machine: every time the compost
is recycled, a certain amount of N-P-K is lost, mainly in the form of
human or farm-animal excrement, but also as direct leaching and evaporation.
One could recycle those wastes, but the recycling will always have a
diminishing return. Of the 3 most important elements, nitrogen is by
far the most subject to loss by leaching, but to some extent that can
also happen with phosphorus and potassium.

In the original "organic
gardening" movement pioneered by Sir Albert Howard in the early
years of the 20th century, nothing but vegetable compost and animal
manure was allowed. In modern organic gardening, on the other hand,
a common technique is to replace lost elements by adding powdered rock,
particularly rock phosphate and granite dust. For "non-organic"
gardeners and farmers, the usual response to the problem of soil replenishment
is to apply artificial fertilizer, N-P-K largely derived from those
same types of rock used in organic gardening. (In fact, the use of rock
powders in present-day organic gardening sounds suspiciously like a
drift toward artificial fertilizers.) If the fragile international networks
of civilization break down, however, then neither rock powders nor artificial
fertilizer will be readily available. They are very much the products
of civilization, requiring a market system that ties together an entire
country, or an entire world.

Writing early in the 20th
century, F.H. King [11] claimed that farmers in China, Japan, and Korea
were managing to grow abundant crops on about 1/10 of the cultivable
land per capita as Americans, and that they had done so for 4,000 years.
What was their secret? The answer, in part, is that most of eastern
Asia has an excellent climate, with rainfall most abundant when it is
most needed. More importantly, agriculture was sustained by the practice
of returning almost all waste to the soil — even human excrement
from the cities was carried long distances to the farms. Various legumes,
grown in the fields between the planting of food crops, fixed atmospheric
nitrogen in the soil. Much of the annually depleted N-P-K, however,
was replaced by taking vegetation from the hillsides and mountains,
and by the use of silt, which was taken from the irrigation canals but
which originated in the mountains. The Asian system, therefore, was
not a closed system, because it took materials from outside the farms,
and these materials came from areas of naturally high fertility.

WHEN WILL MECHANICAL
AGRICULTURE BE ABANDONED?

One way of determining when
oil-based agriculture will be abandoned is strictly economic: when it
costs farmers more money to use machinery than to use hand tools, they
will go back to hand tools. In the study of Mexican labor mentioned
by Pimentel, "a total of 1,144 hours of labor was required to raise
a hectare of corn." Pimentel then compares that labor with the
mechanized corn production in the United States, telling us that "600
liters of oil equivalents [for fuel, fertilizer, and pesticides] are
required to cultivate 1 ha of corn." The ratio of hours to liters
therefore seems to be approximately 2:1.

Modern grain-corn production
in the US, however, results in yields of about 6,000 kg/ha, about 3
times as great as in the Mexican example. If we include that factor
of higher yield, the previous 2:1 ratio of hours/liters must really
be regarded as 6:1.

To discover whether mechanization
is cost-effective, we must insert a number for hourly wage. If the laborer
is self-employed, however, the figure for hourly wage seems purely imaginary:
If costs are rising, for example, can the laborers not simply pay themselves
less? Only to a certain degree. The laborer’s wage is often as
little as it takes to keep body and soul together, but anything less
than that subsistence wage would make farming impossible.

The rise in the price of
fuel, combined with the hourly wage, then, determines the cut-off point
for mechanized labor. When farmers pay themselves a certain amount for
6 hours of work, but the price of fuel is equal to that amount, the
6:1 ratio has been reached, and it would be reasonable for the farmer
to give up mechanization.

Two other factors must be
included if we are to compare manual labor with mechanization. Capital
costs are higher with mechanization: a tractor must be paid for, there
are repairs to consider, and eventually the tractor must be replaced.
For now, however, let us assume that the laborer is working with a minimum
of equipment. Secondly, in spite of what was said above about subsistence
wages, farming income is higher in some countries than in others, and
the same can be said of fuel costs. Farmers in Mexico, with high fuel
costs and low wages, might be inclined to abandon mechanization sooner
than farmers in the United States.

Food, of course, can also
be produced with the labor of horses or oxen, and in fact many hours
of human labor can thereby by saved. Even if animals are fed only on
forage, however, a good deal of land is needed for that purpose. It
is also questionable whether large numbers of horses or oxen could be
bred and distributed in the next few decades. There is also the question
of "alternative energy," in the sense of solutions involving
advanced technology, but such innovations would probably serve little
purpose without fossil fuels to provided at least an infrastructure
[7,8].

What will be the price of
gasoline in a few years’ time? ("Current dollars" are
used here; it is misleading to speak of "inflation-adjusted energy
prices," since it is mainly energy shortages that cause inflation
in the first place [3].) US gasoline prices increased over the quarter-century
before 2003 only at the same rate as the median income [16], with the
exception of some small deviations during periods of warfare. In recent
years, however, prices have risen by 18% per year [6]. With such a growth
trend, a gallon of US gasoline will cost $60 in 2025, and $140 in 2030,
although number-juggling of that sort soon becomes highly speculative.

For the sake of a thought-experiment,
however, we might take a closer look at those price projections. Let
us recall the 6:1 ratio of hours-versus-liters at which it is no longer
cost-effective to use mechanization. A cost of $140/gallon in 2030 would
equal $36/liter. If 6 hours of labor should also happen to cost $36,
a sensible farmer would decide to give up mechanization at that point.
In countries poorer than the US, that cut-off point would actually arrive
well before the year 2030.

The other way of estimating
a cut-off date for oil-based agriculture, of course, is to look at predictions
of the decline in global oil production. According to the latest annual
report of BP Global [1], "proved reserves" are only 1.2 trillion
barrels (excluding a little from Canadian tar sands), although that
figure inches up slightly from one annual report to another. A trillion
barrels of oil is not enough to stretch more than a few decades. A continuation
of an 18% annual increase in the cost of gasoline may seem absurd, but
that figure closely matches the likely bell curve for global oil production:
a decline from 30 billion barrels (5 barrels per person) in the year
2000 to 11 billion barrels (1 barrel per person) in 2030 would be an
average annual decrease of 22%. It is not only gasoline prices and estimated
oil reserves that have an ominous chronological relationship: it is
surely not merely coincidental that there has recently been a spate
of legislation, in several countries, for ethanol and other biofuels,
in spite of the economic and ecological absurdity of such forms of "alternative
energy."

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